A plasma processing apparatus ignites and sustains plasmas by introducing reaction gas containing appropriate etchant or deposition source gas into a vacuum reaction chamber and then inputting radio frequency energy into the vacuum reaction chamber to activate the reaction gas. In this way, through the plasma, a material layer on a substrate surface is etched or a material layer on the substrate surface is deposited, so as to process a semiconductor substrate.
As illustrated in FIG. 1, an existing capacitance-coupling plasma processing apparatus comprises a vacuum reaction chamber 1. Gas inlet means such as a gas shower head 2 provided at top within the reaction chamber 1 implements a function of an upper electrode, so as to couple the shower head to a ground or a radio frequency potential. A base 3 is provided at bottom within the reaction chamber 1. An electrostatic chuck provided on the base 3 and holds a substrate 4 during a process. A lower electrode is provided in the base 3. By applying radio frequency energy to the lower electrode, a radio frequency electric field is formed within the reaction chamber 1, and plasma is generated from the introduced reaction gas. A focus ring 5 is provided surrounding an outer edge of the base 4. By adjusting distribution of the entire radio frequency electric field within the reaction chamber 1, particularly by adjusting electric field distribution at an edge of the substrate 3, the focus ring 5 achieves the regulation of plasma uniformity.
Besides the electrical effect, temperature of the focus ring 5 will also affect deposition of polymers at the edge of the substrate 4, which causes the error of critical dimension. With the etching technique's demands on high aspect ratio process, high power (low frequency) etching processes are widely used which will lead to dramatic rise of the temperature within the reaction chamber 1, such that the substrate 4 and the focus ring 5 will get a lot of heat. In order to ensure etching uniformity of the substrate 4, a cooling medium pipeline of a cooling system that maintains the temperature of the base 3 is provided within the base 3, and the substrate 4 directly performs rapid heat removing through the electrostatic chuck and the base 3. Meanwhile, if the focus ring 5 lack of good heat transferring path, its temperature difference with the substrate 4 will rise. This will cause mistuning of the etching technique at the edge of the substrate 4.
An insulating ring 6 as a heat conducting layer is generally provided beneath the focus ring 5 to transfer heat of the focus ring 5 to the base 3. However, different processes require different working temperatures of the focus ring 5. The prior art only concerns how to enhance heat transfer performance of the focus ring 5 or how to maintain its temperature constant, no one could further controlling and adjusting the working temperature of the focus ring 5. In addition, the focus ring 5 is located within a radio frequency hot region, such that if a temperature adjusting device such as a heater is directly provided in the focus ring 5, not only wire layout becomes complex, but also a filter has to be provided to filter high frequency power; otherwise, a radio frequency interference will occur, which affects the processing effect of the entire apparatus.